This invention relates to an aircraft air conditioning system with at least one compressor, comprising a first conduit which is connected with the pressure side of the compressor and in which one or more cooling means provided downstream of the compressor are arranged for cooling the air compressed in the compressor, and comprising a second conduit designed as bypass conduit, which likewise is connected with the pressure side of the compressor and is arranged such that it conducts at least part of the air compressed in the compressor in a bypass around at least one of the cooling means, wherein a throttle means is arranged in the bypass conduit, by means of which the mass flow of the air conducted through the bypass conduit can be varied.
Aircraft air conditioning systems, which include compressors supplied with ambient air or precompressed air, are known in a number of different embodiments. A problem of electrically driven aircraft air conditioning systems for fresh air supply, air conditioning and pressurization consists in that with a specified mass flow rate, the pressure conditions on the compressor outlet side are changed due to the adjustment of the throttle means arranged in the bypass conduit, which in turn leads to the fact that the temperature of the compressed air is changed as well.
FIG. 1 shows these connections and illustrates that when opening the valve TCV, which is provided in said bypass conduit, the pressure on the valve outlet side drops, which leads to a decrease in temperature. The correspondingly reverse process takes place when throttling the valve TCV, whereby on the one hand the mass flow of the air conducted through the bypass conduit is reduced, but on the other hand the pressure at the compressor outlet is increased, which attenuates or eliminates the effect of the desired change in temperature. Thus, it should be noted that when diverting a partial mass flow around the means provided for cooling with the intention to raise the temperature obtained after recombining the air flows, the transmittance of the total system is increased by opening the valve TCV, which effects, however, that the air temperature at the compressor outlet is decreasing due to the drop in pressure. Depending on the ambient condition, the one or the other effect now prevails. In the extreme case, opening the valve TCV, which per se should effect a supply of warm air, can lead to the fact that the air supplied to the mixing chamber or the aircraft cabin undergoes no change in temperature at all, as the temperature at the compressor outlet has dropped due to the decrease in pressure existing there.
In summary it should be noted that in prior art systems a reproducible correlation between the variation of the opening of the throttle means provided in the bypass conduit on the one hand and the change in temperature realized thereby on the other hand does not exist or can only be realized with difficulty. Therefore, it is the object of the invention to develop an aircraft air conditioning system of the type mentioned above such that the temperature control or temperature regulation is simplified by varying the opening of the throttle means provided in the bypass conduit.